When222Rn concentration is measured with an ionization chamber, the conversion factor of ionization current to222Rn concentration has been decided in individual case. A flow-type ionization chamber (the effective volume; 18l) was used for measuring222Rn concentration in this work. The conversion factor of this ionization chamber was obtained 1.11 (Bq/m3/fA) by the use of RaDEF standard source. From the results of three other literatures and this work, the following formula to calculate the conversion factor (a) was obtained as a function of the effective volume V (m3) of ionization chamber. a=1.036×10-1/V⋅ (log V+6.908) (Bq/m3/fA)
A measurement of222Rn in water, liquid scintillation counting of radon extracted with toluene, was improved: (1) Weight measurement was used instead of volume measurement, (2) solubility approximation equations were revised. These made the experimental operations easier and improved temperature dependence of the radon concentration in calculation, Several solubility data were evaluated by temperature dependence of the radon concentration.
Laboratory experiments on the transfer of Tc from soil to rice and wheat plants have been carried out by using a 95mTctracer, added as TcO4-. The soil-plant transfer factors of Tc for rice plants were ≤50.005 for the grains (hulled) and about 1.1 for the lower leaf blade. In contrast to this, higher transfer factors were found for wheat plants, i. e. 0.027 for the grains (hulled) and 230 for the lower leaf blade. The Tc concentrations in the grains of both plants were lower than in the leaves. The level of Tc in the soil solution collected from the flooded soil was found to decrease rapidly with time. In the case of wheat plants grown in a non flooded soil, the decrease in the Tc level in the soil solution was rather slow. It was suggested that the Tc tracer added as TcO4- to the paddy soil was readily transformed to insoluble forms under the reducing conditions in the flooded soil. The low transfer factor observed for the rice plants could be explained by a fixation of Tc in the soil.
Recent studies have shown that inspite of the radioresistant response of the brain tissue, yet irradiation even at lower doses can affect this tissue and the changes in the levels of some trace elements may be capable of explaining many toxic effects e, g. Parkinsonism is the result of manganese level changes. In this study we used two groups of adult albino rats of both sexes one as a control and the other was exposed to a single radiation dose of gamma rays (60Co) 5 Gy, then some trace elements levels (Fe, Zn, Se, Rb and Br) were measured in the cerebrum, brain stem and cerebellum after a latent period of 2 months by using energy dispersive X-ray flourscenee (EDXRF) analysis. The iron, zinc, selenium and bromine have shown a significant drop in all the brain areas, while rubidium has not shown any change.
99mTc-DTPA-galactosyl human serum albumin (99mTc-GSA) is a new liver-imaging agent which binds to hepatic binding protein. This study evaluated the sensitivity of 99mTc-GSA kinetics and imaging anatomy to hepatic ischemia-reper-fusion injury of obstructive jaundiced rats. Regional hepatic ischemia was induced by clamping the left hepatic artery and the left portal vein for 45 min. The blood clearance and hepatic accumulation indices were obtained on the basis of the dynamic data. A significant difference of these indices was observed between the ischemic group and the control. Marked depression in hepatic99mTc-GSA uptake was observed in the ischemic group. In conclusion, 99mTc-GSA is useful for evaluating the hepatic ischemia reperfusion injury in rats with obstructive jaundice.